Application Security & Protection MCQs

1. What is a computer virus?

a) A hardware malfunction b) A malicious software that replicates itself c) A type of firewall d) An encryption algorithm

Correct Answer: b) A malicious software that replicates itself

Explanation:
A computer virus is malware that attaches itself to clean files and spreads by replicating while performing malicious actions like corrupting data or stealing information.

2. Which of the following is NOT a common type of virus?

a) Boot sector virus b) Macro virus c) Worm d) Antivirus

Correct Answer: d) Antivirus

Explanation:
Antivirus is protective software, not a virus type. Common viruses include boot sector (infects MBR), macro (infects documents), and file infectors.

3. How does a polymorphic virus evade detection?

a) By changing its code structure b) By infecting only text files c) By disabling the antivirus d) By formatting the hard disk

Correct Answer: a) By changing its code structure

Explanation:
Polymorphic viruses mutate their code (using encryption or code rewriting) while maintaining the same functionality, making signature-based detection difficult.

4. What is a Trojan horse in cybersecurity?

a) A virus that replicates rapidly b) Malware disguised as legitimate software c) A type of encryption d) A hardware security module

Correct Answer: b) Malware disguised as legitimate software

Explanation:
Unlike viruses, Trojans don't self-replicate but trick users into installing them by appearing as useful software while creating backdoors or stealing data.

5. Which of the following is a program threat?

a) Phishing b) Logic bomb c) Firewall d) Encryption

Correct Answer: b) Logic bomb

Explanation:
A logic bomb is malicious code that executes when specific conditions are met (e.g., date, event). Other program threats include trapdoors, worms, and rootkits.

6. What is a trap door in software?

a) A backdoor left by developers for unauthorized access b) A type of antivirus c) A hardware security feature d) A network protocol

Correct Answer: a) A backdoor left by developers for unauthorized access

Explanation:
Trapdoors (or backdoors) are secret entry points often left for debugging but dangerous if discovered. They bypass normal authentication mechanisms.

7. Which program threat executes when specific conditions are met?

a) Worm b) Logic bomb c) Spyware d) Adware

Correct Answer: b) Logic bomb

Explanation:
Logic bombs remain dormant until triggered by specific conditions (date/time, file deletion, etc.), then execute malicious payloads like data deletion.

8. What is the primary difference between a virus and a worm?

a) A worm requires user interaction, while a virus does not b) A worm can self-replicate without a host program c) A virus spreads through email only d) A worm is harmless

Correct Answer: b) A worm can self-replicate without a host program

Explanation:
Viruses require host files to spread, while worms are standalone malware that self-propagate through networks (e.g., WannaCry, Stuxnet).

9. Which is NOT a goal of protection in cybersecurity?

a) Confidentiality b) Integrity c) Availability d) Redundancy

Correct Answer: d) Redundancy

Explanation:
The CIA triad (Confidentiality, Integrity, Availability) defines core security goals. Redundancy is an implementation strategy, not a protection goal.

10. What does the principle of "integrity" ensure?

a) Data is accessible only to authorized users b) Data is accurate and unaltered c) Systems are always available d) Data is encrypted

Correct Answer: b) Data is accurate and unaltered

Explanation:
Integrity ensures data isn't modified improperly (accidentally or maliciously). Techniques include hashing, digital signatures, and checksums.

11. Which goal ensures that systems are operational when needed?

a) Confidentiality b) Integrity c) Availability d) Authentication

Correct Answer: c) Availability

Explanation:
Availability protects against disruptions (DDoS attacks, hardware failures) through redundancy, backups, and disaster recovery plans.

12. What is the principle of least privilege?

a) Users should have minimal permissions necessary b) All users should have admin rights c) Encryption should be used everywhere d) Systems should be updated frequently

Correct Answer: a) Users should have minimal permissions necessary

Explanation:
Least privilege limits damage from compromised accounts by granting only the access needed for specific tasks (e.g., regular users shouldn't have admin rights).

13. Which principle ensures that a system remains secure even if one component fails?

a) Fail-safe defaults b) Economy of mechanism c) Complete mediation d) Open design

Correct Answer: a) Fail-safe defaults

Explanation:
Fail-safe defaults means that if a system fails, it should default to a secure state (denying access rather than granting it). This is part of Saltzer and Schroeder's security design principles.

14. What does "complete mediation" refer to?

a) All security checks must be performed every time access is requested b) Only some security checks are necessary c) Encryption is optional d) Users can bypass security

Correct Answer: a) All security checks must be performed every time access is requested

Explanation:
Complete mediation ensures that every access to every object is checked for authorization - systems shouldn't cache or remember previous access decisions.

15. Which principle suggests security mechanisms should be as simple as possible?

a) Economy of mechanism b) Least common mechanism c) Psychological acceptability d) Work factor

Correct Answer: a) Economy of mechanism

Explanation:
Economy of mechanism (also called simplicity) states that security designs should be small and simple enough to be verified and implemented correctly.

16. What does the "open design" principle mean?

a) Security should not depend on secrecy of design b) All source code must be public c) No encryption should be used d) Systems should have no authentication

Correct Answer: a) Security should not depend on secrecy of design

Explanation:
Open design means security should rely on keys/passwords rather than keeping algorithms secret (Kerckhoffs's principle). This allows for public scrutiny of the design.

Application Security & Protection MCQs

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